1. Field of the Invention
The invention relates to a color cathode ray tube (CRT) and, more particularly to the manufacturing of a luminescent screen assembly having at least one color filter.
2. Description of the Related Art
A color cathode ray tube (CRT) typically includes an electron gun, an aperture mask, and a screen. The aperture mask is interposed between the electron gun and the screen. The screen is located on an inner surface of a faceplate of the CRT tube. The aperture mask functions to direct electron beams generated in the electron gun toward appropriate color-emitting phosphors on the screen of the CRT tube.
The screen may be a luminescent screen. Luminescent screens typically comprise an array of three different color-emitting phosphors (e.g., green, blue and red) formed thereon. Each of the color-emitting phosphors is separated from another by a matrix line. The matrix lines are typically formed of a light absorbing black, inert material.
In order to enhance the color contrast of the luminescent screen, a pigment layer, or color filter, may be formed between the faceplate panel and the color-emitting phosphor. The color filter typically has a color that corresponds to the color of the color-emitting phosphor formed thereon (e.g., a red-emitting phosphor is formed on a red pigmented filter). The color filter transmits light that is within the emission spectral region of the phosphor formed thereon and absorbs ambient light in other spectral regions, providing a gain in color contrast.
The color filters are typically formed using a subtractive process in which the filter layer is deposited on the interior of the faceplate panel, and, in a subsequent development process, select portions of the filter layer are removed. Unfortunately, for resist-based color filter formulations, agglomerates may form when the pigment is mixed with the resist polymer (e.g., polyvinyl alcohol (PVA) or polyvinyl pyrrolidone (PVP). Agglomerates may undesirably lead to non-uniform pigment distribution within the color filter. Additionally, it is difficult to harden resist-based color filter formulations that contain pigments having strong absorption peaks below 500 nm, reducing the line-width control of the color filter.
Thus, a need exists for a method of forming a color filter cathode ray tube (CRT) that overcomes the above drawbacks.